Selective catalytic reduction (SCR) may be used to treat exhaust gases from combustion-type power plants such as internal combustion engines or other fuel burning devices to remove certain types of pollutants. For example, a reducing agent may be introduced into an exhaust gas stream in the presence of a catalyst to remove NOx compounds from the exhaust gases and replace them with gases such as water vapor, nitrogen, and/or carbon dioxide. Urea is one example of a reducing agent that may be used in an SCR system. SCR systems may be configured to deliver stored reducing agent to an injector or other delivery point located at an exhaust system component to disperse or insert the agent into the exhaust stream to be treated.